1. Field of the Invention
The present invention generally relates to thermometers with components that react to changes in temperature by changing color, such as thermochromic liquid crystals (TLCs). More particularly, the invention concerns an apparatus or article of manufacture comprising a multi-colored decal such as an animal, flower, fish, or other design with spots or other features that individually reveal or display a message, depending upon temperature. According to the decal""s current temperature, an appropriate one of the temperature sensors, normally camouflaged within the features of the decal, is activated and thus becomes visible.
2. Description of the Related Art
Temperaturee sensing devices come in a variety of forms, with various underlying scientific principles. One recent type of thermometer uses TLCs, usually constructed in a planar shape. TLCs react to changes in temperature by changing color. These materials are made of twisted molecular structures comprising optically active mixtures of organic chemicals. TLCs include cholesteric compositions, chiral nematic formulations, and combinations of the two.
TLCs show colors by selectively reflecting incident white light. xe2x80x9cTemperature-sensitivexe2x80x9d mixtures in thin films reflect bright, almost pure colors. They turn from colorless (black, against a black background) to red at a given temperature, and pass through the other colors of the visible spectrum in sequence as temperature increases. This progression includes orange, yellow, green, blue, and violet. At an even higher temperature, the crystals turn colorless (black) again.
In contrast to temperature-sensitive mixtures, xe2x80x9ctemperature-insensitivexe2x80x9d formulations reflect just a single color below a given transition temperature, changing to colorless (black) above this temperature. These formulations are sometimes called xe2x80x9cshear-sensitivexe2x80x9d or xe2x80x9cclearing pointxe2x80x9d mixtures. TLC formulations have also been developed that provide a bandpass feature, reflecting a single color within a prescribed temperature range, otherwise changing to colorless (black).
TLCs have been implemented in a variety of forms. One of the most prevalent examples is a temperature strip made by placing numerous TLC rectangles end to end. The rectangles are arranged so that, as the ambient temperature changes from lowest to highest readable temperature, the rectangles are individually illuminated sequentially from one end of the strip to the other. This is done by using bandpass-type TLC rectangles with sequentially increasing activating temperatures. One example is the reversible temperature sensor, part A5321, manufactured by Hallcrest, Inc. of Glenview Ill. With this particular part, the TLC in each rectangle is shaped into numbers defining the corresponding temperature sensed by that rectangle, such as xe2x80x9c74.xe2x80x9d
TLC materials are used in many different product configurations. For example, some temperature strips are attached to a background border printed with certain textual information. For example, the border may include evenly marked numerical increments of temperature, a temperature scale (e.g., Celsius) that contrasts with that shown on the temperature strip, etc. With other products, the border material includes a cartoon drawing, ruler, or other non-textual information. In some cases, the printed border design provides a decorative function unrelated to the temperature strip; in other configurations, the printed border provides data with some relation to the temperature strip.
Although some of the thermometers discussed above enjoy widespread commercial success today, the present inventors have sought to improve the utility and operation of known thermometers.
Broadly, the present invention concerns a decal with multiple temperature sensors that individually appear within certain concealing features of the decal in accordance with different prescribed temperatures, otherwise blending into the concealing features and thereby disappearing into the design. The decal may depict an image of an animal, fish, flower, abstract form, or another design, such as a photograph, cartoon, sketch, or other representation. The image includes multiple separate concealing features, such as spots, fins, flower petals, abstract shapes, or other components of the decal""s image. These features may have one color in common, or different concealing features may have different colors. The feature color(s) contrasts with one or more background colors in the design, which serve to visually separate the concealing features. The temperature sensors are scattered throughout the design in a visually pleasing manner. Importantly, the sensors are placed within the concealing features, where the non-activated color of each temperature sensor matches its surrounding concealing feature. Thus, non-activated sensors become camouflaged within their surrounding feature color(s).
The temperature sensors comprise a formulation that reacts to changes in temperature by changing color, and may comprise a thermochromic liquid crystal (TLC) material, for instance. Each temperature sensor is activated by a different ambient temperature range. As an example, each activated sensor may display a number representative of the corresponding temperature range, such as 78xc2x0 F. Instead of numbers, the sensors may display other themes such as various colors, words, graphics, alphanumerics, etc. As a particular example, sensors may indicate various comfort or safety zones by displaying messages such as xe2x80x9ctoo warm,xe2x80x9d xe2x80x9cjust right,xe2x80x9d or xe2x80x9ctoo cold.xe2x80x9d Thus, according to the decal""s current temperature, an appropriate one of the temperature sensors is activated, causing it alone to arise from its otherwise hidden position in one of the image""s concealing features.
Each temperature sensor may be located apart from any others, i.e., no two sensors in the same concealing feature. Alternatively, temperature sensors may be arranged in different groups, where each group of sensors resides in the same concealing feature. Additionally, the invention also includes arrangements with a combination of grouped and solo sensor distribution. In many cases, it may be desirable to provide a design where the image and the temperature sensors are flat. However, surfaces with some desired contour may be used if required.
Accordingly, as discussed above, one aspect of the invention is an apparatus or article of manufacture, embodied in a decal with multiple concealing features that selectively display or conceal temperature sensors, according to the ambient temperature. Another aspect of the invention involves a method for manufacturing such a thermometer.
The invention affords its users with a number of distinct advantages. For example, many users will find these thermometers to be significantly more attractive and interesting than the often sterile, mathematical TLC strips of the past. Furthermore, animal owners seeking to provide a more authentic animal habitat for their pets will find the present thermometer decal to be more natural, and less visually distracting. Users may find particular benefit for this thermometer in aquariums, terrariums, solariums, and other microhabitats. Furthermore, other applications may include shower doors, windows, and other safety, environmental, or ornamental applications.
Among other uses, this thermometer may be implemented as an adhesive bandage or refrigerator magnet. The thermometer of this invention may be built with heat blocking backing, to increase the utility of the invention for indicating ambient temperature despite being mounted to warm or cool surfaces (such as a terrarium or outside window). Conversely, the thermometer maybe constructed for the reverse effect, namely to insulate the thermometer from ambient temperatures and encourage conductive heat transfer with the mounting surface. As another advantage, an adhesive tie coat may be incorporated into the manufacturing process to preserve temperature sensors made of cholesteric inks, which can exhibit poor adherence due to the brittle, grainy nature of such inks. Also, the invention offers enhanced visual effects, achieved through techniques such as the coordinated multiple activation of temperature sensors, incorporation of holograms, etc.
The invention also provides a number of other advantages and benefits, which should be apparent from the following description of the invention.